Refrigerating apparatus



July 26, 1938.

A. o. GROOMS REFRIGERATING APPARATUS Filed Aug. 30, 1934 6 Sheets-Sheet1 July 26, 1938. A. o. GROOMS REFRIGERATING APPARATUS Filed Aug. 50,1934 6 Sheets-Sheet 2 \WJ \Q A 7 3 DQ\ h \I|\ m an 0% nu &3 a? Q mm mbamb NR. y .1 mw R R2 lw T JF 11mm July 26, 1938. A. o. GROOMSREFRIGERATING APPARATUS Filed Aug. 30, 1954 6 Sheets-Sheet 3 k mww y 6,1938; A. o. GROOMS 2,125,070

REFRIGERATING APPARATUS Filed Aug. 50, 1954' 6 Sheets-Sheet 4 DEGREES FJuly 26, 1938.

A. O. GROOMS REFRIGERATING APPARATUS Filed Aug. 50, 1934 6 Sheets-Sheet6 T 45' TIC DEFROS 0N SEMPAUTIM" CUT cur-o/v FULL nuroMnT/c DEFROST ENoRMH 25 *CUT-ON L1, 20 u a /s Q L OWLE F NORM F I E a T-OFF Q K i 0 7 54 3 Z H B COLD CONTROL POSITIONS No./ COLD CONT/P01. POSITION 4 5 6 TIMEH OURS INVENTOR.

U Zwmwi/ ATTORNEYS Patented July 26, 1938 PATENT orFlcE REFRIGERATINGAPPARATUS Albert 0. Grooms, Dayton, Ohio, assignor to General MotorsCorporation, Dayton, Ohio, a corporation of Delaware Application Augustso, 1934, Serial No. 742,125

14 Claims.

This invention relates to refrigerating apparatus and more particularlyto control means therefor.

Heretofore, it has been proposed to provide the control means of arefrigerating system with a plurality of selective control features,such as a quick freezing cycle control, a defrosting cycle control,temperature regulation and periodic defrosting. With so many selectivefeatures available for the user, it is quite often that one or more ofthe features are not returned to the normal or ineffective positionbefore selecting and manipulating another of the control features. Undersuch conditions, the feature selected would usually fail to operate orbe delayed in its operation,

often causing considerable trouble and unpleasantness to the user.

It is an object of my invention to provide a refrigerating system with acontrol means having a plurality of convenient selective features providing different forms of operation, any one of which is effective toovercome the setting of the other to immediately give effect to the lastselected setting.

It is another object of my invention to provide a refrigerating systemwith a control means capable of providing continuous cyclical operationof the system at different selected average temperatures, as well as toprovide for a single cycle of operation at a lower temperature for quickfreezing and an optional single cycle of operation at a highertemperature for defrosting, and for periodic higher temperature cyclingfor periodic defrosting of the evaporator.

It is a further object of my invention to provide a means within thesystem for adequately protecting the refrigerating apparatus to preventits operation under conditions capable of damaging the apparatus.

Further objects and advantages of the present invention will be apparentfrom the following description, reference being had to the accompanyingdrawings, wherein a preferred form of the present invention is clearlyshown.

In the drawings:

Fig. 1 is a view of the refrigerating system partially diagrammatic,including my improved control means;

Fig. 2 is a sectional view taken along the line 50 2-2 of Fig. 1,showing a portion of the temperature regulating mechanism with theselective temperature regulator in the closed position;

Fig. 3 is a plan view of a temperature regulating knob in the positioncorresponding to the 55 setting shown in Fig. 2;

Fig. 4 is a sectional view taken along the line 2-2 of Fig. 1, showingthe temperature regulating mechanism set for the warmest temperatureprovided by the temperature selector;

Fig. 5 is a plan view showing the temperature selecting knob in theposition corresponding to the setting shown in Fig. 4;

Fig. 6 is a view taken along the line 6-6 of Fig. 1 with the quickfreezing mechanism in ineffective position;

Fig. 7 is a sectional view on the line 6-6 of Fig. 1 with the quickfreezing mechanism in effective position;

Fig. 8 is a vertical sectional view showing the manual on and offcontrol with the contacts in open position;

Fig. 9 is a vertical sectional view of the manual on and off controlwith the contacts in closed position;

Fig. 10 is a vertical sectional view of the overload protecting andresetting apparatus with the apparatus in properly set condition; and

Fig. 11 is a vertical sectional view of the overload control with theapparatus in the tripped condition.

Fig. 12 is a graph with temperature plotted against cold controlpositions showing the cuton and cut-off temperatures for the normalcycle, the semi-automatic and full automatic defrost and the quickfreezing cycle in the various cold control positions.

Fig. 13 is an illustrative chart having temperature plotted against timeshowing typical normal full automatic, quick freeze and semi-automaticdefrost cycles with the cold control in No. 1 position.

Referring to the drawings and more particularly to Fig. 1, there isshown a refrigerating system including a compressor for compressingrefrigerant and for forwarding the compressed refrigerant to a condenser2i where the compressed 1 refrigerant is liquefied and collected in areceiver 22. From the receiver 22, the liquid refrigerant is forwardedunder the control of a suitable control means 23 such as an expansionvalve or restrictor to an evaporator 24 located within an insulatedcompartment 25 to be cooled. The compressor 20 which withdraws theevaporated refrigerant from the evaporator and pumps it into thecondenser is driven by an electric motor 26 under the control of acontrol means 21 located in series with the electric motor 26 in theelectric motor circuit 28. The control means 21 is controlled accordingto the temperature of .he evaporating means through a thermostatic bulb29 which is charged with fluid refrigerant and connected by a conduit 38with the control means.

The conduit 36 connects with a metal bellows 3i which is fastened at itslower end by the nut 32 to an L-shaped bracket 33 which in turn israstened by the screws 3% and 35 to the depending portion 3t and thetransverse plate portion 31 of the metal framework of the control means.The expansion of the metal bellows is limited by an inverted L-shapedmetal member 38 which passes through apertures in the L-shaped bracket33 to hold it in position. The upper or free end of the metal bellows 3!is provided with a pointed projection. lil which passes through anaperture in the inverted L-shaped stop member 38 and engages a recess inthe primary lever M This pri-- mary lever ii is provided with notches 42which engage and form a pivotal connection with a depending metal plateportion 33 of the metal framework. The free end of the primary lever Mis provided with an insulating portion it provided with an enclosed pairof notches which receive the pointed end of the secondary lever 65,which in turn is connected by the toggle spring 55 with the anchor postat of a bell crank lever. This bell crank lever is formed of one portionit which carries the anchor post ll and also provides stopping means forthe secondary lever '55 and which is riveted to the contact carryingportion 49 pivoted by a pivot pin 50 to the adjacent wall of theinsulated box shaped enclosure 58. This contact carrying portion carriesthrough the medium of a universal connection a contact bar 52 which isadapted to bridge a pair of switch contacts 53 which are situated onebehind the other in Fig. 1.

When the temperature of the evaporating means 25 is high, the volatileliquid within the thermostatic bulb 29 vaporizes, causing the pressurewithin the bellows 3! to increase and move the primary lever 46 in acounter-clockwise direction on its pivot point, thereby moving thepivotal connection between the primary and secondary lever upwardlyacross the dead center line of the toggle spring as, so that the togglespring will puli the free end of the secondary lever 65 downwardlyagainst the horizontal portion of the bell crank contact carrying lever,thereby causing the bell crank contact carrying lever to be moved in acounter-clockwise direction about the pivot pin 50 to cause the contactbar 52 to engage and bridge the contacts 53 to close the electric motorcircuit 28. This will cause the omration of the electric motor 26 andthe refrigerating system which will reduce the temperature of theevaporating means and the thermostatic bulb 29 so that the volatileliquid wiil condense within the thermostatic bulb 29 and reduce thepressure within the bellows 3i.

The reduction of pressure within the bellows 36 will permit the primarylever M to be moved in a clockwise direction about its pivot point underthe influence of the tension coil spring 5% which is connected to adownwardly turned ear 55 formed of a part of the primary lever iii. Thisclockwise movement of the primary lever i! will move the pivotalconnection between the primary lever ti and the secondary lever 45downwardly so as to cause the free end of the secondary lever E5 to snapupwardly against the stop portion of the member 38 of the contactcarrying bell crank lever so as to cause the bell crank lever to turn ina clockwise direction about its pivot pin 50 until it engages thedifferential adjusting screw 55 which engages the projecting portion 56on the bell crank: iever. This difierential screw 55 is threaded througha guide plate 5? and is provided with a locking not for holding it inposition. The differential screw 55 by determining the open contactposition of the bell crank lever determines the difference in thebellows pressure between contact opening position and contact closingposition.

For a fixed tension or the control spring 5% and a fixed setting of thedifferential screw 55, the contacts 52 and 53 are opened and closedaccording to predetermined temperatures of the evaporator 26, such as 5and which is a common setting in ordinary household refrigerators.

Referring now more partcularly to Fig. 2, the lower end of the controlspring 5 2 is connected to a lever Bil pivoted at its midpoint to a pinBi and connected at its opposite end to a slide or carriage 62 threadedupon the temperature regulating screw 63 which is rotatably mounted inthe transverse frame portion 3'8 of the control means. This temperatureregulating screw 63 is provided with a splined head 68 which receives acollar 65 having a serrated aperture and a projection 66 adapted tocooperate with a pin 6? to limit the free rotation of the screw 63 to asingle turn so as to limit the temperature adjustment of the controlmeans. The splined head 66 also receives a temperature regulating knob68 pro- Vided with an indicating arrow which cooperates with theindicating dial 69 to indicate the various positions of temperatureregulation designated B, A, and i to i inclusive. The temperatureregulating knob 88 serves as a means for providing a limited temperatureregulation for the user. If further temperature regulation is desired,it is necessary to remove the temperature regulating knob 68 and thecollar 55, then turn the temperature regulating screw 63 the desiredamount and replace the collar 65 and the temperature regulating knob Win the same relative position with respect to the pin 5? and the dial'59, in

order to provide a new range of temperature regulation for the user. Ifdesired, this temperature range may extend above the freezing point. soas to cause frost to melt from the evaporator when the temperatureregulating knob is set in its warmest, or B position. However, prefer tohave the temperature regulating range extend entirely below freezingtemperatures.

This, however, causes frost to continuously ac cumulate on theevaporatorand I have, therefore,

provided automatic means of an imnroved type for removing this frost.This frost acts as an in sulator, and therefore, prevents the efilcientcooling of the enclosure by the evaporator 26.. In

order to keep this amount of frost at a minimum, I have provided meansfor periodically varying the operation of the control means so as tocause a temperature above freezing to be attained in the evaporator 26so that the frost will melt there from.

This is performed by a ratchet wheel which has fixed thereto a memberwith a projection i i. This ratchet wheel iii and the member li are ro--tatably mounted upon a pin I2 which is anchored in the insulating endportion it of the primary leverfii. The ratchet wheel Hi and theprojecting portion or pin ii are rotated by an anchor type of member 13which is pivoted upon a pin M extending from the primary lever 65. Thisanchor member i3has atail portion 15 and a small compression type coilspring 16 extends between this tail portion andthe primary lever so asto urge the anchor member is in a clockwise di rection about the pivotpin it. The anchor member 13 has a tooth 11 at its upper end adapted toengage the ratchet wheel Ill and another tooth 18 also adapted to engagethe ratchet wheel. The portion of the anchor member which carries thetooth 18 is adapted to engage a platform 79 formed on the dependingportion 36 of the control frame. When the bellows 3| contracts, theprimary lever 46 moves in a clockwise direction carrying the ratchetwheel 10 and the anchor member downwardly. As the primary lever 4|,

approaches switch opening position, the lower portion of the anchormember 73 which carries the tooth 78 comes to rest upon the platform l9.Further downward movement of the primary lever 3i causes the switchcontacts to be opened and causes the tooth T8 to be moved toward theratchet wheel. This mechanism is similar to the common escapementmechanism of a timepiece but operates somewhat differently.

After the switch contacts close, the primary lever 4| continues to moveunder the influence of the tripped toggle spring 46 and during thismovement, the tooth 18 engages the inclined side of one of the teeth ofthe ratchet wheel 10 just beyond the tip thereof so that furtherdownward movement by the coaction of the tooth 18 on the anchor member13 with the inclined face of the tooth on the ratchet wheel will movethe ratchet wheel in a clockwise direction through an angular distancecorresponding to something less than the arc of a single tooth. Byrotating the ratchet wheel on the overtravel of the primary lever 45after the switch contacts have been opened, the cut-off point of theswitch is not affected by the ratcheting. The opening of the controlcontacts causes the stopping of the refrigerating system, thuspermitting the temperature of the evaporator to rise and thereby causingthe pressure to increase within the bellows 3|.

This will cause the primary lever H to begin a counter-clockwisemovement, during which time the anchor member 73 will slowly rotate in aclockwise direction about its pivot pin 14 under the influence of thecoil spring 15 which maintains the portion of the anchor member 13 incontact with the platform 19. During the middle portion of thismovement, the upper tooth ll of the anchor member comes into engagementwith the inclined face of one of the ratchet teeth near its mid-pointand upon further movement of the primary lever 4i, rotates the ratchetwheel through the angular distance corresponding to half a tooth untilit engages the bottom of the depression between the teeth. In this way,the ratchet wheel is rotated a predetermined accurate amount for eachcycle of the refrigerating system.

When the projection or point H is rotated to its upper verticalposition, it engages the projection 15a which resiliently opposes theupward movement of the primary lever ll. Through this means, there isimposed once every revolution of the ratchet wheel an additionalresilient resistance to the expansion of the bellows 3i so that anincreased pressure within the bellows corresponding to a temperature ofthe evaporator 24 above 32 F. is required before the bellows and theprimary lever Ii may move a sufiicient distance so as to cause thecontrol contacts to be closed to again start the refrigerating system.By increasing the temperature of the evaporating means above 32 F., thefrost begins to melt from the evaporator. After sufficient pressure isat tained to close the contact under such conditions, the ratchet wheelmoves downwardly and again comes into engagement with the tooth 78, sothat the projecting portion of pin H is moved from its vertical positionso that it will not again engage the resilient projection "59a until thesucceeding revolution of the ratchet wheel. During a normal cycle, theprojection or point H is at some other position so that it does notengage the projection 19a and no additional resistance is providedresisting the movement of the primary lever to switch closing position.

The resilient projection 19a is a tooth or projection formed on the endof a transverse lever 80 (see Figs. 2 and 4) which is pivoted upon a pin8i fixed to the control frame and which is resiliently urged in aclockwise direction about its pivot pin 88 by a tension coil spring 82which is connected to an ear 83 formed on the carriage 62 of thetemperature regulating mechanism. Thus, when the temperature regulatingcarriage is moved downwardly, corresponding to a movement of thetemperature regulating knob to a lower temperature position, the spring32 is stretched and thereby the tension upon the spring 82 is increased.Inasmuch as a lesser resistance to the expansion of the bellows isprovided in the lower temperature position, this increase in tension ofthe spring 82 will compensate for the lower temperature regulatingposition so that the temperature secured by the defrosting cycle remainssubstantially the same.

The defrosting spring 82 is provided with an adjustment by beingconnected at its upper end to a threaded member 85 which carries anadiustlng nut 36 resting upon the upper side of the lever 80. Theposition of the lever 80 is controlled by an arm 87 which is pivotedupon the bracket 88 extending from the control frame and which incooperation with the compression spring 89 and the finger manipulator 90forms a toggle mechanism. The arm 3'! is provided with a chisel shapedend M which is held in a notch 92 formed in the finger manipulator bythe compression spring 89 which extends between the bracket 88 and anadjusting nut 93 which is threaded upon a threaded pin at extending froman aperture in the bracket 88 to the yoke portion of the arm 8'! andserving as a guide for the spring $9.

By this toggle device, the arm 8? as well as the finger manipulator atare held in either one of two positions. In the position shown in Fig.l, the finger manipulator 953, which is pivoted upon the pin 9t to apair of ears 95 extending from the member 63, is shown in its extremecounter-clockwise position, while the arm 87 is shown in its extremeclockwise position; When the finger manipulator til is moved in aclockwise direction across the dead center line of the toggle mechanism,the arm 87 under the force of the toggle spring 89 moves to its extremecounterclockwise direction and lifts up the projection i911 and thelever 80 so that the projection ltd is up out of the path of theprojecting portion of the pin it connected to the ratchet wheel 79.This, therefore, prevents the occurrence of the periodic defrostingcycle.

In order to provide means for obtaining a single defrosting cycleindependently of the periodic defrosting cycle, I provide a link $77which extends between the armd'l and the primary lever ti, so that whenthe finger manipulator 9%) is in its extreme clockwise position, anadditional resistance is provided which opposes the expansion of thebellows 30, thereby increasing the pressure required therein beforethecontact bar 52 may be moved to.a closed circuit position. The link 97is formed of heavy sheet metal or metal plate and has shoulders restingupon the arm ill and the primary lever ll together with projectionsextending therethrough. When the bellows 3i has expanded a sufiicientamount, the primary lever ll through the link 9i will move the togglemechanism upwardly across the dead center position, so that the fingermanipulator 10 so and the arm 31 will move under the force of the togglemechanism to their extreme counter-clockwise and clockwise positionsrespectively, whereby the link W is pulled upwardly such a distance thatit will not be engaged by the primary lever. In order to discontinuesuch a defrosting cycle, the finger manipulator may be moved manually atany time to this position.

If desired, however, either one of these defrosting features may beomitted, so that one of the positions of the finger manipulator 90 maybe used to prevent any defrosting. Thus, if it is desired to provide acontrol means without a pcriodic defrosting device, the ratchet wheel,together with the projecting pin, the transverse lever and its springmay be omitted from the device, leaving the arm 81, the toggle mechanismand the link 9'5 as a single cycle defrosting device. On the other hand,if it is desired to omit the single cycle defrosting device, then thelink 9i is omitted but the ratchet wheel together with the projectingpin, the transverse lever and its spring are retained for periodicdefrosting. When one of these devices is omitted, the former operatingposition of the finger manipulator for the device omitted becomes theposition for shutting off the defrosting device retained.

As better shown in Figs.- 6 and 7, I have also provided a quick freezingdevice which provides a single low temperature cycle. To operate thisdevice, 1 have provided a button tilt located within and movable withinthe center of the temperature regulating knob 68. This knob is fastenedto the upper end of a rod ldi which extends down through the center ofthe temperar ture regulating screw 63. This rod also passes through abracket it? which is riveted to the depending portion 36 of the switchframe. The lower end of the rod tilt is provided with a head its whichis adapted to engage one end portion of a toggle member its which ispivoted upon the pin Hi5 carried by the bracket me. The toggle member W3is connected by a tension coil spring ltd with a threaded member Edicarrying an adjusting nut W8 which rests upon the carriage $2 of thetemperature regulating mechanism. The toggle member ltd has a foot m9formed thereon which engages, when moved into the position shown in Fig.7. a molded depending portion Mil formed on the primary lever M. Thistoggle member tilt is moved into this position by pushing downwardlyupon the button iilii ch through the rod moves togglemember ltd .e: withits spring ltd across its dead cenposition, so the foot resilientlyengages e under side of the depending portion Mil. in way, a resilientobstruction or resistance is placed in the path of the downward movementoi the primary lever ti which then requires a lower pressure within thebellows 3i corending to a much lower temperature oi the vaporatlng means25 before the contact bar 3e moved to circuit position.

en a sufdcien. v low temperature is obto i the prima.;, er movesdownwardly and the depending portion lit by its engage= areaoro mentwith the foot its moves the toggle member mil and the toggle spring wein a clockwise direction across the dead center position to itsineffective position shown in Fig. 6. The temperature attained by thisquick freezing cycle is maintained substantially constant regardlessofthe setting of the temperature regulating screw 63, since the positionof the temperature regulating screw and temperature adjustment iscompensated because the upper end of the toggle spring we is anchoredthrough the threaded member not and the adjusting nut E08 to thecarriage 62 of the temperature regulating mechanism and the downwardmovement of the carriage to a colder position setting contracts andweakens this toggle spring we. Thus, through separate springs connectedto this carriage, both the defrosting mechanism and the quick freezingmechanism are compensated so that the temperatures attained by thesemechanisms are not substantially affected by the setting of thetemperature regulating knob 68.

In my control mechanism, I have also provided a convenient means wherebythe refrigerating system may be turned on and shut off. In order to dothis without disturbing or imposing any added strain upon the partsoperated by the bellows 3|, I have provided a separate set of contacts029 located within the insulated enclosure 5! directly opposite thecontacts .53 and located one behind the other in a somewhat similarmanner. These contacts are adapted to be bridged by a contact bar lEflwhich is connected by a universal connection to a contact lever l22which at its mid-point is pivoted upon the pin H23 fixed to theinsulated enclosure. The opposite end of the lever B24 is connected by atoggle spring to a foot 825 forming part of a finger manipulator E26pivoted upon the pin l2l fixed within the insulated enclosure 5!. Theconnection between the end portion 926 and the foot I525 is provided bya small compression spring lid which at its opposite ends engages theconically pointedspring retainers H29 and lid which are retained insuitably formed recesses in the end portions 924 and 525. The springretainer 629 has a rod tel extending therefrom which extends into atubular portion I32 extending from the spring retainer 836, so as toform a guide for the spring lid. Through this mechanism, when the fingermanipulator 925 is moved toward the left in counter-clockwise directionabout its pivot pin, the contact bar. lfil is moved to open circuitposition with a snap action, whereas when the finger manipulator ismoved to the right in a clockwise direction about its pivot point, thecontact bar ml is moved to closed circuit position with a snap action.

in connection with this toggle circuit controlling mechanism I haveprovided a thermal overload mechanism which will positively prevent theoperation of the refrigerating system under overload conditions. Inorder to do this, I take ad-= vantage of the excessive flow of currentthrough the electric motor circuit under overload conditions. For thispurpose, I have provided a nickel chromium heater wire 535 located inseries-with andconnecting the contacts 53 and 5%. This heater wire iscoiled about a brass pin 53% fixed to the rear wall of the insulatedenclosure 5i and provided with a ratchet wheel l3? fixed thereto by asuitable fusible binder such as a suitable solder which will melt orbecome fusible when an overload current pames through the electric cirecult and generates heat within the coil of the heater wire I35. Thisratchet wheel is normally engaged by a latch formed of a leaf spring I38which is riveted to a slide bar I39. This slide bar is slidably mountedby being received within apertures of a U-shaped metal supporting means51 which is riveted to the rear wall of the insulated enclosure Thisslide bar I39 is at one end provided with a lip I40 for engaging thecontact lever I22 and pulling it toward open position and also a pair ofears which receive a pin I M upon which is pivotally mounted a resettinglink I42.

When in a properly set position illustrated in Fig. 10, the ratchetwheel I 37 is held in a fixed position by the fusible binder upon thepin I 35 and the leaf spring riveted to the slide bar then engages theupper teeth of the ratchet wheel I31, so that the slide bar I39 and theresetting link I42 are prevented from moving toward the right. However,when an overload current passes through the heater wire I35, the fusiblebinder becomes soft, thus permitting the ratchet wheel to turn upon thepin I36 thereby releasing the leaf spring I38 and permitting the slidebar I39 to move to the right under the influence of the tension springI43 which is anchored to an ear I51 formed on the U-shaped bracket 5'I.

As the slide bar I39 moves to the right, another tension spring Iddwhich connects the resetting link I 42 with. the upper portion of thebracket 5! exerts more of an influence and moves the free end of theresetting link I42 outwardly so that it assumes the position shown inFig. 11.

In order to reset this overload mechanism, an engaging arm I45 isprovided on the finger manipulator I26 so that it may engage theshoulder I41 upon the free end of the resetting link I42. Furthermovement of the finger manipulator I26 in a clockwise direction movesthe free end of the resetting link I42 to the left and during thismovement, the curved portion I48 upon the resetting link engages theportion 56 (see Fig. l) of the bell crank contact carrying lever, sothat the temperature regulating contacts are held in their open positionduring the resetting of the thermal overload contacts. During thisresetting operation, the toggle mechanism in the ordinary manner movesthe overload contacts to closed circuit position, while the temperatureregulating contacts are held in the open position. Thus, therefrigerating system is protected in this way during the resetting ofthe overload contacts.

When the overload contacts are moved to closed circuit position, and theresetting link and the slide bar are moved to the left, the leaf springI38 again engages the upper teeth of the ratchet wheel I38 and preventsthe movement to the right of the slide bar I39. During this movement ofthe resetting link to the left, the toggle spring I43 becomes stretched,so that the resetting link I42 is pulled downwardly as soon as pressureis released on the finger manipulator I25. This moves the resetting linkout of engagement with the projecting portion 53 of the contact carryingbell crank lever to permit the temperature regulating contacts to closeas well as out of the path of the engaging portion IIE of the fingermanipulator I 2E.

When the overload mechanism is tripped, the overload contacts are pulledto open position, the toggle mechanism is pulled across dead center andthe finger manipulator I26 is moved to open position, thereby giving anindication that the refrigerating system is shut off. By holding opensetting and by disengaging the resetting link I42 after resetting theoverload contacts, the system is protected at all times from overloadand it is impossible to interfere with the proper operation of thetemperature regulating contacts or to prevent the proper operation ofthe overload mechanism.

While the form of embodiment of the invention as herein disclosed,constitutes a preferred form, it is to be understood that other formsmight be adopted, all coming within the scope of the claims whichfollow.

What is claimed is as follows:

1. Refrigerating apparatus including an evaporator and means forsupplying liquid refrigerant to and for withdrawing evaporatedrefrigerant from the evaporator, control means for normally controllingsaid supply means to normally maintain said evaporator at freezingtemperatures, said control means including a common means capable ofassuming a plurality of positions having a portion for periodicallyaffecting the control to provide temperatures above freezing when in oneposition and having another portion effective when the common means isset in another position to render the periodic portion of the commonmeans ineffective and to affect the control to automaticaly provide atemperature of the evaporator above freezing and thereafter againrendering the periodic portion of the common means effective andautomatically returning the apparatus to normal control.

2. Refrigerating apparatus including an evaporator and means forsupplying liquid refrigerant to and for withdrawing evaporatedrefrigerant from the evaporator, control means for normally controllingsaid supply means to normally maintain said evaporator at freezingtemperatures, said control means including means for periodicallyaffecting-the control to provide temperatures above freezing,compensating means for said periodic means, and selective means forpreventing the periodic means from aifecting the normal action of thecontrol means in any way.

3. Refrigerating apparatus including an evaporator and means forsupplying liquid refrigerant to and for withdrawing evaporatedrefrigerant from the evaporator, control means for starting and stoppingthe supply of liquid refrigerant according to predetermined temperaturesof the evaporator, selective means for periodically changing one of thetemperature limits for a single cycle and thereafter returning theapparatus to normal control, a second selective means for varying theaverage temperature of the evaporator, and means for compensating saidfirst mentioned selective means according to the temperature variationprovided by said second selective means.

4. Refrigerating apparatus including an evaporator and means forsupplying liquid refrigerant to and for withdrawing evaporatedrefrigerant from the evaporator, control means for starting and stoppingthe supply of liquid refrigerant according to predetermined temperaturesof the evaporator, selective means for periodically raising one of thetemperature limits and thereafter returning the apparatus to normalcontrol, selective means for lowering one of the temperature limits andthereafter returning the apparatus to normal control, and a separateselective means for varying the temperature limits to obtain a differentaverage temperature, and means controlled by said last mentionedselective means for'comp'ensating said first two selective means iii forchanges in said separate selective means.

5. Refrigerating apparatus including an evaporator and means forsupplying liquid refrigerant to and for withdrawing evaporatedrefrigerant from the evaporator, control means for starting and stoppingthe supply of. liquid refrigerant according to predeterminedtemperatures of the evaporator, selective means for periodically raisingone of the temperature limits and thereafter returning the apparatus tonormal control, a

second selective means independent of said first mentioned selectivemeans for lowering one of the temperature limits and thereafterreturning the apparatus to normal control, said selective means being soarranged that any selected will overcome the other selective meansregardless of their position.

6. Refrigerating apparatus including an evaporator and means forsupplying liquid refrigerant to and for withdrawing evaporatedrefrigerant from the evaporator, control means for starting and stoppingthe supply of liquid refrigerant according to predetermined temperaturesof the evaporator, said control means including overload means forpreventing operation of the supply means and selective means forpreventing operation of the supply means and for resetting the overloadmeans and restoring the normal operation of the control and supplymeans, said selective means including means for preventing at all timesthe manual relocking of the overload means in reset position regardlessof any manipulation of the selective means.

'7. Refrigerating apparatus including an evaporator and means forcirculating a refrigerant medium through the evaporator, control meansfor controlling the circulation of refrigerant through the evaporator tomaintain a predetermined average temperature therein, said control meansincluding a loading means and an escapement type mechanism forperiodically causing the loading of the control means by the loadingmeans for varying the average temperature of the evaporating means.

8. A control means for refrigerating systems or the like including apressure operated means and a means operated thereby, an adjustablemeans for applying an adjustable load upon the pressure operated means,said adjustable means comprising a carriage and a loading spring meansconnecting the carriage and the pressure operated means, and a manuallyinitiated single cycle loading device for loading the pressure operatedmeans for a portion of a cycle,said single cycle loading device having aspring connected to the carriage for compensating the single cycleloading device for the eifect of the change of position of the carriageupon the loading spring means.

9. A pressure responsive circuit controlling means for refrigeratingsystems or the like including means for opening and closing an electriccircuit and pressure responsive means connected thereto for causing thecircuit to be opened and closed at predetermined pressure limits, aratchet wheel for periodically interposing a resistance to the movementof the pressure responsive means to cause the circuit to be opened andclosed at other pressure limits, and escapement type actuating means forratcheting said ratchet wheel according to reciprocations of thepressure responsive means,

10. Refrigerating apparatus including a cooling unit and means forcirculating a refrigerant medium through the cooling unit, control meansfor normally controlling the circulation of refrigerant medium accordingto predetermined high and low temperatures afiected by the circulationof the refrigerant medium, a periodic device indexed ever'ycycle by thecontrol means solely at other temperatures than'the said predeterminedhigh and low temperatures, said periodic device including meansperiodically eifective for disturbing the normal operation of thecontrol means to disturb one of said temperature limits.

l1. Refrigerating apparatus including a cooling unit and means forcirculating a refrigerant medium through the cooling unit, control meansfor normally starting and stopping the circulation of refrigerant mediumaccording to predetermined high and low temperatures affected by thecirculation of the refrigerant medium, a

periodic device indexed every cycle by the control means solely at othertimes than the starting and stopping of the circulation of refrigerantmedium to avoid disturbing the starting and stopping points, saidperiodic device including means periodically effective for disturbingthe normal operation of the control means to disturb one 'of saidtemperature limits;

l2. Refrigerating apparatus including a cooling unit and means forcirculating a refrigerant medium through the cooling unit, a movablecontrol means movable to one position to start the circulation of therefrigerant medium according to a predetermined high temperaturecondition, said movable control means being movable to a second positionto stop the circulation of refrigerant medium according to apredetermined low temperature condition, a periodic device indexed everycycle by a portion of the movement of the control means which does notinclude said starting and stopping positions to avoid disturbing therelationship between the predetermined temperatures and the starting andstopping of the.

circulation, said periodic device including means periodically effectivefor disturbing the normal operation of the control means to disturb oneof said temperature limits.

13. In a control for refrigerating systems or the like, a circuitopening means and a pressure responsive means for operating said circuitopening means to open and close an electric circuit, and amechanism-operated by the pressure responsive means for periodicallydisturbing the normal operation of the pressure responsive means, saidmechanism including a ratchet wheel for disturbing the normal operationof the pressure responsive means, and a rocking member having aplurality of teeth for ratcheting said ratchet wheel, one of said teethbeing effective to ratchet the wheel when the rocking member is rockedin a clockwise direction and another being efiective to ratchet thewheel when the rocking member is rocked in a counterclockwise direction.

14. A control means for refrigerating systems or the like includingpressure operated means and a means operated thereby, an adjustablemeans for applying an adjustable load upon the pressure operated means,said adjustable means comprising a carriage for a loading spring meansconmeeting the carriage and the pressure operated means, and a singlecycle snap acting loading device for applying a load to the pressureoperated means for a portion of a cycle only, said single cycle loadingdevice having a spring connected to the carriage for compensating thesingle cycle ioading device for the efiect of the change of position ofthe carriage upon the loading spring means.

ALBERT O. GROOMS.

